Such an acquisition system for example includes a sensor for measuring at least one physical variable, for example the position, speed, ambient temperature, pressure or humidity.
The measured physical variable is transmitted to the acquisition system for example in the form of an electrical resistance, or more generally in the form of an analog signal.
The acquisition system then makes it possible to transform this analog signal into a digital signal that can next be processed by a suitable digital processing means and optionally be communicated to an operator.
Thus, the acquisition systems are usable in many technical fields.
This is particularly the case for on-board avionics systems for example making it possible to measure the temperature outside the aircraft using a suitable sensor.
The operation of such acquisition systems must therefore meet a certain level of criticality or safety generally imposed by aeronautics standards based on the significance of the applied physical variable and/or its influence on the piloting of the aircraft.
Thus, for example, aeronautics standards ARP 4754A, ED-12C and DO-178C define five levels of criticality (from A to E) or DAL (Design Assurance Level) for avionics systems. The DAL A level has the highest criticality level and is assigned to avionics systems whereof an operating defect may cause a catastrophic event in the aeronautics sense of the term (loss of human life).
The DAL A level is for example assigned to various acquisition systems usable in DAL A avionics systems. This requires many constraints regarding the operating safety of these systems. One can then see that development, production and operating costs for the systems become increasingly high with the increase in the number of these constraints.
Thus, to decrease these costs while retaining the overall DAL A criticality level of the avionics system, it is known to use several redundant acquisition systems with a lower criticality level, for example DAL B. Different voting systems may next be applied by the avionics system to choose the majority value from among all of the values delivered by these redundant acquisition systems.
Furthermore, to avoid aging of these systems, their criticality level is often oversized in production, which makes it possible to ensure their proper operation over the entire operating period despite any aging.
One can then see that this results in a certain number of drawbacks, which include electricity consumption, bulk, complexity, weight and high costs of these acquisition systems.
Furthermore, the existing acquisition systems often have limited abilities to detect flaws in their operation and make it possible to detect only sudden flaws of the straightforward failure type.